BioEd Online

If you want to lose weight, stop worrying about which diet is most effective and simply pick whatever programme you find easiest to follow. That's the advice from nutrition experts in the United States, who have found that dieting success seems to depend on how closely people stick to a diet, rather than which one they choose.

Physicians around the world have sounded alarm bells about the increasing number of people who face problems due to unhealthy eating. Globally, there are over 1 billion overweight adults, according to the World Health Organization.

At the same time, the range of dieting options has also grown. Advertisements and books promote plans such as the Zone diet, which aims for a 40:30:30 ratio of calories from carbohydrate, fat and protein, respectively. Recent studies have also drawn attention to the controversial Atkins diet¹,², which minimizes carbohydrate intake without restricting fat.

But the relative effectiveness of these diet plans and others remains poorly understood. A review article published this week, for example, warns that many commercial and self-help weight loss programmes do not have satisfactory evidence to support their claims³.

Weighing the benefits

To test how four popular diets compare, Michael Dansinger of the Tufts-New England Medical Center in Boston and his colleagues randomly assigned 160 overweight adults to one of the four programmes. These included the Atkins and Zone plans, along with the Weight Watchers diet, which recommends restriction of portion size and calories, and the Ornish diet, which suggests a vegetarian diet containing only 10% of calories from fat.

At the start of the study, the men and women averaged 106 kilograms and 93 kilograms, respectively. The participants attended classes to help them get started on their diet plan, and the researchers checked on their progress with questionnaires and monthly calls.

After a year, Dansinger and his colleagues found that in each diet group about a quarter of the volunteers had lost more than 5% of their initial body weight. But they saw no difference between the four groups.

Sticking point

The researchers did see a big difference, however, between those who stuck to their diets, and those who did not. The third of participants who followed their programmes most closely lost on average 7% of their body weight, compared with roughly half that for the group as a whole. The findings appear this week in the Journal of the American Medical Association⁴.

The result may sound intuitive, but Dansinger and his colleagues say they hope to challenge the idea that alternative diets are unimportant and that one weight-loss strategy is best for everyone. Instead, they recommend that people select whatever approach suits them best.

"Different diet plans can work for people. The major issue is what their preference is," says Dansinger's co-author Ernst Schaefer, of Tufts University in Boston.